Traction Adding battery to rear of garden tractor for weight + more power. CCA Question?

Doofy · Nov 26, 2019

Tired of wimpy "Lawn Tractor" battery in my Suburban Lawn Tractor with 36" Snow Blower with electric lift.

Old car battery I want to use reads 12.5 volts after charging and holds a charge well. The CCA rating on the battery is 540 and when tested with the tester, it says "Bad" with a actual CCA of 350 amps.

Will this battery still be an improvement even with diminished CCA capability? Not wanting to buy a new battery. Thanks

Roadworthy · Nov 27, 2019

If it'll hold a charge it should source plenty of current for the much smaller lawn tractor starter motor.

jaydee325 · Nov 27, 2019

Was that a load test on the battery that said bad? If so, the battery is shot and you are wasting your time.

Wired in parallel a bad battery will act as a parasitic load to the good battery.

12.5 volts is only about 90% fully charged. If that is only as high as you can get the voltage during a charge, that is further indication the battery is no good.

Doofy · Nov 27, 2019

jaydee325 said:
Was that a load test on the battery that said bad? If so, the battery is shot and you are wasting your time.

Wired in parallel a bad battery will act as a parasitic load to the good battery.

12.5 volts is only about 90% fully charged. If that is only as high as you can get the voltage during a charge, that is further indication the battery is no good.

View attachment 630314

I don't think my electronic battery tester does an actual load test but it somehow figures out the CCA and fails the battery on that info. The battery does charge to 100% (12.6v) but is usually down to 12.5v a couple days later.

JDAOWNER · Nov 27, 2019

I THINK A FULLY CHARGED 12 V BAT SHOULD READ ABOUT 13 PLUS VOLTS.

tomplum · Nov 27, 2019

My electronic tester will call a battery bad if it is less than 75% of the entered CCA. SO your battery is PROBABLY just fine. A trip to the auto parts store for an actual load test may be in order before too much work would go into it. That way you know more about it holding a load. A battery can pass the electronic test and fail a load test though. Of course, if it doesn't work- the store has new batteries.

tomplum · Nov 27, 2019

JDAOWNER said:
I THINK A FULLY CHARGED 12 V BAT SHOULD READ ABOUT 13 PLUS VOLTS.

12.6 actually 2.1 per cell

Doofy · Nov 27, 2019

tomplum said:
My electronic tester will call a battery bad if it is less than 75% of the entered CCA. SO your battery is PROBABLY just fine. A trip to the auto parts store for an actual load test may be in order before too much work would go into it. That way you know more about it holding a load. A battery can pass the electronic test and fail a load test though. Of course, if it doesn't work- the store has new batteries.

Nothing ventured- nothing gained. I think I will try it, at least get my cables made and ran to the back of the tractor. If my battery is to far gone, not a big deal to just buy a new one. The CCA of the existing garden tractor battery is 230 amps and the car battery is at 350 CCA. If it holds a charge, it should have a better reserve.

Doofy · Dec 11, 2019

Watched a Youtube video of folks installing a full sized auto battery to their lawn tractors. By golly, it fit. All I had to do was remove the old lawn tractor battery and it's plastic tray and crimp a new end on the existing battery cable. Big improvement.

Deere Dude · Dec 12, 2019

My free wimpy little garden tractor that I used for a runabout had a bad battery mounted under the seat. I had a spare heavy duty truck battery from a battery update in my diesel dually so I mounted that on the trailer hitch and lengthened the cables to fit. It's not ideal but works and was free. Easier to pull wheelies now.